The present invention relates to a method of activating an inactive terminal of a data network, which terminal is connected to a telephone network, for establishing a connection through the data network between a further terminal and the terminal to be activated. The invention also relates to a server of a data network, to an adapter unit connected between a terminal of a telephone network and the telephone network, to a telephone, and to a microcomputer, preferably a personal computer, comprising a modulator-demodulator (modem) or an ISDN adapter.
The present invention relates to the field of telephony over data networks, particularly to the field of telephony over Internet Protocol (IP) networks, so-called Internet telephony.
It is known in the art to use IP networks (e.g., the Internet or intranets) for telephony. Internet telephony, also referred to as “Voice over IP” (VoIP), is expected to find wide use, because it provides considerable cost savings over conventional telephone calls through the telephone network, particularly in the case of long-distance and international calls. For VoIP, both the calling party and the called party must have terminals with Internet access. To be able to make a call through an IP network, both terminals must be connected to the Internet. Connections between the terminals and the Internet are commonly established through the telephone network at the local call rate. The actual long distance between the calling party and the called party, which is very expensive in the case of a conventional voice call over the telephone network, is covered via the IP network, in which rates are generally very low.
There are various methods for carrying out VoIP. An essential difference between the methods lies in the type of terminals used. Frequently, use is made of multimedia-capable personal computers (PCs) on which suitable software for transmitting speech data over the IP network is installed. This permits telephony from PC to PC via an IP network. Using suitable compression techniques, the amount of data to be transmitted over the IP network can be reduced to about 8 to 12 kb/s. If sufficient bandwidths are available, speech quality is acceptable and corresponds to that in mobile radio networks.
In PC-to-PC telephony, however, the circle of users is greatly limited, since a large number of potential users of Internet telephony do not have a PC or a suitably equipped PC. Therefore, Internet telephony solutions are being offered in which an interface from a conventional telephone network to an IP network is implemented using a so-called gateway. This permits VoIP between a PC and a conventional telephone (analog or ISDN) or even between two telephones.
In Internet telephony via gateways, the calling party dials the number of a first gateway, which is located as close to the caller as possible. The connection to the gateway is established through the conventional telephone network. Next, the calling party dials the number of the desired party. The first gateway then establishes an IP connection through an IP network to a second gateway, which is closest to the called party. From the second gateway, a conventional telephone connection is then established to the called party.
In the prior art, providers of Internet telephony must maintain a gateway in as many local networks as possible so as to enable users of Internet telephony to access the IP networks nationwide at the lowest possible rate (the local rate). However, the installation and maintenance of the gateways is very expensive and nullifies most of the cost advantages offered by Internet telephony. This is one of the main reasons why Internet telephony has not yet become accepted.